Catheters have been developed for many treatment and diagnostic applications for various organs (e.g., heart, brain, bladder, etc.) and systems (vascular, alimentary, etc.) of the body. Examples of common catheter-based treatment applications include coronary heart disease (e.g., stent placement, angioplasty, coronary artery bypass, etc.), arrhythmia (e.g., electrophysiology, pacemaker electrode placement, transvenous placement of epicardial leads), cardiac septal defect repair, heart valve repair (e.g. valvuloplasty and percutaneous valve implantation), congestive heart diseases (e.g., providing segmental-myocardial pacing), aneurysms (e.g., placement of vaso-occlusive devices), arteriovenous fistulas (e.g., for dialysis), creation of artificial contacts or shunts between two cardiac chambers as a bridging treatment for certain congenital heart diseases, shunting veins of the portal systems and the inferior cava vein; as well as in intracardiac imaging approaches, which necessitate transseptal navigation of the imaging catheter. As such, catheters serve many functions including, but not limited to, applying energy (e.g., microwave, RF, ultrasound, etc.) to tissue to stimulate nerves, ablating tissue or tightening enlarged orifices, and acting as a conduit for the delivery of implants (e.g., stents, shunts, etc.), instruments (e.g., cutting tools, etc.) other devices (e.g., balloons, filters, etc.) and fluids (e.g., saline, drugs, etc.) to within the body for dilating obstructions or removing growths.
During a catheterization procedure, the physician delivers one or more catheters to a target site within an organ (typically a hollow organ or a chamber within an organ) and/or within a tissue lumen, and attempts to engage a target anatomical structure for one or more of the purposes mentioned above. Catheter delivery often requires navigation through tortuous pathways and passing the catheter through walls of an organ or lumen to access the target site, which target site may be in another organ or lumen or otherwise adjacent the wall being passed through. Often times the passage(s), pathway(s) or hole(s) created to access the target site must be closed upon completion of the procedure due to bleeding or other complications that may occur. Thus, quite frequently, these procedures involve perforating, piercing, cutting, suturing, incising, obliterating, cauterizing, and coagulating tissue, both at a target site and at one or more locations along the delivery pathway of the catheter.
With advancements in endovascular and percutaneous delivery technologies, many more kinds of procedures are able to be performed without invasive or open surgery. One ongoing objective is to reduce the profiles of the delivery catheters and, thus, the procedural instruments as much as possible in order to minimize trauma to the patient and to enable access through very small spaces and vessels. Catheter size (diameter) reduction is particularly challenging in complex procedures that require a variety of different tools (e.g., a cutting instrument and an implant delivery tool) to be delivered to the target site. Even if the size objectives are achieved, it is usually at the sake of procedure time as the number of instruments that can be simultaneously delivered through a catheter is limited. Quite frequently, only one instrument can be delivered and used at a single time.
The venous circulation system, which connects to the right heart, presents a large-caliber, low-pressure conduit system. Some approaches use the venous system to deliver medical devices to the arterial system at the heart level by creating an artificial communication between the two systems.
Virtually all aspects of catheter-based procedures require assisted visualization. Usually, catheterization of hollow organs, especially the heart, is performed under x-ray imaging, e.g., fluoroscopy. Fluoroscopic imaging represents the gold standard for guidance of catheterization procedures because it provides excellent overview on a body-segment and organ level. Although powerful in visualization of dense structures such as bones, prostheses, and other aspects of gross anatomy, fluoroscopy is not as suitable for imaging soft tissue structures, such as muscle and fatty, or fibrous tissues (such as heart valves, various segments of the myocardium, and major afferent or efferent vessels of the heart). Another commonly used modality of medical imaging is ultrasound. Although very effective in visualizing soft tissue, the use of ultrasound in the guidance of catheters has not reached adequate popularity in catheterization laboratories due to technical and logistical limitations.
Without proper visualization, the more likely inaccuracies may occur in the location of tissue augmentation or removal and/or the extent of an intentional disruption or removal of tissue. For example, the location of the actual perforation or penetration site may be mistakenly made a distance from the intended penetration site or, while the location of the penetration or incised site is correct, the size of the hole, cavity or incision created may be larger than is necessary for the particular application.
With the current limitations of visualization technologies and catheter-based instruments, there is still a need for improvement to catheter systems which address the aforementioned shortcomings of the prior art. It would be additionally beneficial if such catheter systems made the endovascular procedures easier, reduced space requirements and minimized procedure time.